Safety device for electric lamp housing



April 24, 1956 G. GORHAM 2,743,351

SAFETY DEVICE FOR ELECTRIC LAMP HOUSING Filed March 5, 1951 2Sheets-Sheet l H6. 6. l INIENTOR. 660466 Gaff/4M 92 35 BY 54% M 1- April24, 1956 SAFETY DEVICE FOR ELECTRIC LAMP HOUSING Filed March 3. 1951 G.GORHAM 2,743,351

2 Sheets-Sheet 2 2,743,351 SAFETY- DEVICE FOR ELECTRIC LAMP HOUSINGGeorge Gorham, New York, N. Y., assign-or toScopicon, Iuc., BronxCounty, N. Y., a corporation oi New York Application March 3, 1951,Serial No. 213,729 2 Claims. (Cl; 240-2) high voltage to the apparatusupon opening a closure thereof.

The primary object of the present invention is the provision of agenerally improved and simplified interlock device which isautomatically operable upon the opening of. a closure. toremove'th'esupplyof'voltage to mechanism accessible when theclosure isopen.

Another object is the provision ofa simple interlock mechanism which isoperable to control the actuation of a plurality-of switches.

A further object is the provision of an interlock mechanism whichnormally opens the electric circuit when the housing closure is openedbut which'can be operated by the electrician under special conditions tocomplete the, circuit when the closure is opened to obtain access to theinterior of the light housing.

The above and other objects, featuresand advantages of the presentinvention willbe moreiully understood from the followingdescriptionconsidered in connection withthe accompanying illustrativedrawings.

In the drawings:

Fig. 1 is a-perspective view of .a lamphousingand electricaldistribution .box thereforembodyiug the present invention, the lamphousing being shown with the closure thereof inv open condition;

Fig. 2. is a sectional viewtaken along.the.line.22 .of Fig. ,1,'theclosure being in the closedcondition. thereof;

Fig; 3lis .a sectionalview takenon the line 3-3.of g! Fig. 4-isa detailview illustrating aportion of the switch mechanisminthe open or circuitinterrupting condition when the closure. is: opened;-

Fig. 5 is a detail view with the switch mechanism when manually operatedto close-the switch when under repair or other special conditions; and

Fig; 6 is a simplified. circuit diagram.

The present inventionis illustrated and described in connection withthe. lamp'housingof a'micro-projector of the type disclosed in PatentNo.v 2,477,396 to Edwin C.'Weiskopf, datedJuly 26, 194 9, andisprimarilyv intended fOT'HSE in connection. with a highvoltage lamp ofthe-type -used in such projectors.

Referring nowtoFig. 1, there is illustrated a lamp housing Ill) of thetypefully illustrated and described in" the aboveridentified patent.Saidv housing. is provided at'the frontthereof with a closure or door.12 which is 734,585, filed March 14, 1947, now Patent No. 2,569,876,dated October 2, 1951, but which may be a single lamp as illustrated insaid first mentioned patent. Water conduits for cooling said lamps areindicated at 20 and 22. The individual lamps 24 and 26 are preferably ofthe high voltage mercury vapor type and the voltage therefor is suppliedby an insulated cable 28 which has a terminal 3i). Cable 23 is of a wellknown type which comprises connected to a terminal of plug 30 and thesheath which is electrically connected to bracket 27 is electricallyconnected to a grounded part ofsaid plug. The secondany of an electrictransformer is electrically connected to said plug in the manner whichwill be presently described.

The lamp housing is provided with an electrical dis tribution andcontrol box 32 which may be mounted thereon in any suitable manner, suchas for example, by meansof bracket rods indicated'at34. Saiddistribution box is preferably formed of suitable sheet metal and isprovided on the front wall 35-thereof with a low voltage socket 36 forreceiving a detachable terminal plug 38 of the supply line 46 which maybe connected to any convenient source of alternating current or"ordinary low voltage, preferably 116 volts. A terminal connector block42 is mounted-in a chamber 44 provided in the front wall of thedistribution box 32 above the socket 36. Said terminal block is providedwith a set of low voltage terminals 46 and with a set of high voltageterminals 48. Box 32 is also provided with a plurality of low voltageoutlet receptacles 5i"! to supply power for operating various auxiliarydevices. as in saidPatent No. 2,477,396. It will be understood that allof the low voltage terminals and outlet receptacles or sockets 46 and5f; are connected in parallel to the input receptacle 35 to which thelow voltage plug 33 is connected. More particularly, the low voltagereceptacle 36 is provided with the wires 52 and 54 which areelectrically connected to the wires 56 and 53, respectively, at theterminals 6% and 62, respectively, of the switchesG-d and 65. it will beunderstood that the low voltage outlets 5d are connected in parallel tothe wires Edand 58. As. here shown, switches 64 and 66 are preferably ofthe microswitch type, but it will be understood that any other suitableswitches may be used. Wires as and '73 connect the switches 6 3 andomrespectively, to the low voltageterminals 46 of the connector block 42so. that said terminals46. are energ-ized'when said switches are closedand deenergized when said'switches are open. As illustrated anddescribedin the first mentioned patent, a low voltage distribution lineis-used to connect the low voltage terminals eta-or the distributicn'boxto the primarywinding P (Fig. 6) ofa step-uptransfcrmer in the powerunit of theapparatus iilustt ted and described insaid patent. Asshown insaid first mentioned patent, the highvoltage from the secondary S ofsaid transformer is connected to the high voltage terminals 48- ot thedistribution box to provide the high voltage required for the lamps 2a.and 26. Referring to Fig. lot the drawings hereof, one of saidhighvoltage terminals this connected through a wire 72 to a. terminalreceptacle or socket 74 in which the previously mentioned: plug isremovably received. The other high voltageterminal -48 is connectedthrough a wire 76 to a grotnidingbracket 78 which issecured inany-suitable manner'to the distributiombox 32. Awire 80 extends fromsaid grounding bracket to the receptacle '74 for completing the highvoltage supply line to the lamp unit 13. Therefore it will be apparentthat the switches are in circuit with the lamp unit. The low voltagereceptacle 36 is also connected to said grounding bracket through thewire 82.

Due to the presence of high voltage in the lamp housing 10, safety meansare provided to eliminate the danger of personal injury which would bepresent in case access to the interior of said housing could be obtainedwhen high voltage is connected to the lamp unit 18. For this purpose,and pursuant to the present invention, there is provided a safety deviceor interlock mechanism which is operable by the closure 12. Saidinterlock mechanism comprises the'interlock member 84 and the switchactuating parts 86. More particularly, the distribution box 32 isprovided with a shelf 87 which extends transversely thereof between thelow voltage socket 36 and the terminal block 42. As here shown, saidshelf is provided with a depending lateral flange 88 which is secured tothe wall 90 of the distribution box in any suitable manner, such as at92. The shelf is also provided with the bent-up opposing end portions 94and 96 respectively, which are spaced from the adjacent housing walls 35and 100, respectively, as illustrated in Fig. 2. Each of said endportions is provided with an aperture 102 through which the interlockmember 84 extends.

The micro-switches 64 and 66 are arranged in tandem, said switches beingmounted on the upper surface of shelf 87, and each of said switches isprovided with a switch operating member 103 which is normally biased tothe circuit interrupting or open condition of the switch. Each switch isalso provided with a flexible actuating member 86 formed of any suitablespring metal. As illustrated in Fig. 3, one end of the actuating member86 is secured to the switch and said member extends therefrom as at 104and overlies the switch operating part 103. The free end 105 of theactuating member is reflexed for a purpose hereinafter described. Itwill be understood that switches 64 and 66 are normally open switches inthat the companion contacts of each switch are automatically separatedwhen the actuator pins 103 are released. Switches of this type are wellknown and as they do not per se form part of the present invention,further description thereof is unnecessary.

As here shown, the interlock member 84 is in the form of a metallic rodor spindle which is provided with the circumferentially notched portions106 and 108 disposed in spaced relation longitudinally of said rod.Adjacent the notched portion 108, rod 84 is provided with a portion 110of reduced diameter to form the circumferential shoulder 112. Saidportion 110 is disposed in the aperture 102 and extends through anaperture 98 in the housing wall 100, being provided adjacent the freeend thereof with a stop 114. A helical compression spring 115 isprovided on said portion 110 between the shoulder 112 and the shelfportion 96. The other end 116 of rod 84 extends through an aperture 118provided in thehousing wall 35.

It will be noted that the rod 84 is disposed laterally of the switches64 and 66 adjacent the side thereof on which the actuating member 86 ismounted. The closure 12 is provided with a part 122 which extendslaterally therefrom to engage the end 116 of rod 84 when the closure isin the closed position thereof and retains the latter against movementoutwardly of the front wall 35. With the closure in the open positionthereof, illustrated in Fig. 1, the rod 84 is biased by the spring 115to the position thereof illustrated in broken line in Fig. 3, in whichposition the end 116 thereof is moved outwardly of housing wall 35 andthe opposing end is moved inwardly relative to housing wall 100. In saidposition of the rod 84, the recesses or notches 106 and 108 registerwith the reflex ends 105, respectively, of the companion actuating parts86. Said parts, being formed of spring metal, reflex bodily so that thereflexed ends 105 thereof engage in the adjacent complementary shapednotched portions, as illustrated in Fig. 4. In this manner, said partsmove away from the companion switch operating members 103, permittingthe latter to move under their own bias to open the switches. It will beapparent that since said switches are connected in the low voltagecircuit to the primary of the high voltage transformer, that in saidposition of the rod 84, the input to the transformer is interrupted sothat there is no high voltage output available from said transformer forthe lamp assembly 18. Therefore, in this condition of the apparatus,access may be had to the interior of the lamp housing without danger ofinjury.

Upon closing the door or closure 12 of the lamp housing, the part 122carried thereby engages the end 116 of rod 84, as illustrated in Figs. 2and 3, and moves the latter in the direction of arrow A in Fig. 3, andas illustrated, in the full line position of the parts, so that thenotched portions 106 and 108 are moved out of engagement with the reflexends of the companion actuating parts 86. In this condition, the reflexends engage the outer surface of the rod 84 and are flexed therebytoward the companion micro-switches to depress the companion operatingparts 103 and close said switches. it will be apparent that in thiscondition of the mechanism, there is a completed low voltage circuit tothe primary of the high voltage transformer so that the high voltage ispresent in the lamp housing for the lamp assembly. Upon subsequentreopening of the closure 12, the rod 84 will be released for movement inthe opposite direction, as indicated by the arrow B in Fig. 3, by thecompressed spring 105, so that the notched portions 106 and 108 will bein position to be engaged by the reflex ends 105 of the switch actuatingparts 86 to interrupt the high voltage supply. It will be noted thatthis requires only a comparatively small movement of the rod 84 in thedirection of arrow B so that the high voltage is discontinued to thelamp housing when the closure 12 has been moved a similar comparativelyshort distance in the direction of the opening thereof, said latterdistance being insufficient to permit the entry of a hand into the lamphousing. Therefore, the high voltage supply is always interrupted beforethe closure 12 is moved from the housing sufliciently for a person toreach into the interior thereof. Also, it will be understood that since,as above explained, the power unit of the apparatus shown in said firstmentioned patent is supplied from the terminals 46 which in turn aredisconnected from the source of supply when switches 64 and 66 areopened, the transformer and all other electric devices in the power unitare de-energized when the closure 12 is moved to its open position (Fig.1). It will be noted that switches 64 and 66 are disposed in the twosides of the electric circuit so that they constitute double poleswitching means to interrupt both sides of the supply lines to the powerunit and hence to the lamp in the housing when the door 12 is opened.

In the event that it becomes necessary, for purposes of repair ormaintenance, to provide high voltage in the lamp housing with the dooror closure 12 in the open position thereof, this can be accomplished bya service man or electrician who is familiar with the operation of theinterlock mechanism. In this connection, with the door 12 open, the rodend 116 can be grasped and pulled in the direction of arrow B in Fig. 3so that the reflex portions 105 ride out of the companion recessportions and onto the outer surface of the rod rearwardly thereof, asillustrated in Fig. 5, for flexing the parts 86 to close the switches.When rod 116 is manually moved to the position illustrated in Fig. 5, toclose the switches 64 and 66 under special conditions even though door12 is open, as just explained, spring is ineffective to return said rodto its normal switch-open position and said rod remains stationary inswitch-closed position by the frictional engagement of members 104 withsaid rod. However, when. the door is closed, member 122 pushes said rodto its normal switch-closed position (Fig. 3) ready to be moved byspring 115 to its switc -open position when the door is opened.

While I have shown and described the preferred em- Having thus describedmy invention, what I claim and desire to secure by Letters Patent, is:

1. In an electrical device having a main and an auxiliary housing, thecombination comprising a movable closure means for said main housing, apair of terminals on said auxiliary housing adapted to be connected to alow voltage energy source, a step up transformer within said auxiliaryhousing, a high voltage illuminating device in said main housing, lowvoltage circuit means for supplying cnergy from said terminals to saidtransformer, high voltage circuit means for supplying energy from saidtransformer to said illuminating device at the proper high voltage,means for controlling both said high and low voltage circuit means,comprising a pair of switches interposed in said low voltage circuitmeans between said terminals and said transformer, a rod slidablymounted in said auxiliary housing and having a pair of notches definedtherein, each of said switches having an actuating gethcr, spring meansfor biasing said rod to a first position in which both said notches aremoved into engagement with said switch actuating parts whereby tooperate said switches to open said circuit means, a portion of said rodextending outwardly of said auxiliary housing and being operativelyengageable with said closure for moving said rod to a second positionwhen said closure is moved into closing relationship with said mainhousing, said notches in said rod being disposed to one side of saidopen said circuit means when said closure is moved out of closingrelationship, said rod being adapted to be manually moved longitudinallyto a third position in connected to a low voltage energy source, a stepup transformer in said auxiliary housing, low voltage circuit means insaid auxiliary housing, at least a branch of said circuit meansextending from said terminals to the primary winding of saidtransformer, and high voltage circuit means extending between saidauxiliary housing and said main housing and connecting said illuminatingdevice to the secondary winding of said transformer, and meanscontrolling said low and high voltage circuit means, comprising a pairof switches disposed in said auxiliary housing and interposed in saidlow voltage circuit means and adapted to open and close said low voltagecircuit means whereby to energize and deenergize both said low and highvoltage circuit means, a rod having a pair of notches defined therein,said rod being slidably mounted in said auxiliary housing and having a.portion thereof extending outside said auxiliary housing, each of saidswitches having an actuating part comprising an elongated spring armengaging said slidable rod, said spring arms being positioned relativeto said rod so that both move into and out of their associated notchesin unison whereby to open and close, respectively, their associatedswitches, said portion of said rod extending moving said rod out of saidthird position, whereby both said circuit means can be energized whensaid door is out of closing relation with said main housing.

References Cited in the file of this patent UNITED STATES PATENTS

